Document: AND-3-43-10

Differences in the density of saltmarsh-inhabiting phytophagous insects along a natural salinity gradient.

HUBERTY, A.F.* and R.F.DENNO

Unversity of Maryland, College Park, MD USA ¹

Abstract:
Plant stress has been traditionally viewed as a strong force underlying the population dynamics of herbivorous insects. Previously, we conducted laboratory experiments to determine the impact of salt-stressed plants on an assemblage of saltmarsh-inhabiting herbivorous insects, mostly planthoppers and leafhoppers. The results of these studies suggest there is no generalized response governing the performance of insects on stressed host plants; even congeners show divergent responses. Thereafter, we conducted a survey of low- and high-salinity marshes to determine if naturally-occurring salt stress in the field would elicit similar herbivore responses found in the laboratory studies. We sampled 16 saltmarshes along the Chesapeake Bay and 4 Atlantic coastal marshes to span the range of desired salinities. To a great extent, results of the field survey corresponded to laboratory findings. Species which responded adversely to salt stress in the laboratory (e.g. Prokelisia dolus) occurred more abundantly on low-salinity marshes, and species that were positively affected by salt-stressed plants in the lab (e.g. Prokelisia marginata) occurred more commonly on the saline marshes. Both our field and laboratory data cast doubt on the plant-stress hypothesis as a general explanation for the outbreak dynamics of herbivorous insects.

Keywords: stress, plant-insect interactions

This abstract is being presented at: 1:15 PM in session:
Oral Session #65: Wetlands, Estuaries and Salt Marshes.